The present invention generally relates to portable, hand-held fluid testers for measuring the properties of a test fluid in the field. More particularly, it relates to a new and improved portable, hand-held fluid tester having improved sealing and assembly, electrical connection and fluid volume control features.
Hand-held fluid testers are currently available for measuring electrical conductivity of a process fluid such as boiler fluids or coolant fluids. These fluid testers include a fluid reservoir which contains electrodes to measure the electrical conductivity of the fluid in the reservoir. The electrodes are connected to a circuit board via jumper wires. Some models also include a thermistor to provide temperature compensation for more accurate measurement. If employed, the thermistor is typically mounted in a hole adjacent the fluid reservoir with a thin wall separation which sometimes breaks into the reservoir. These thermistors are usually connected to the printed circuit board via jumper wires. In some models, the thermistor is potted into place with a potting compound to both assemble the thermistor to the fluid reservoir and to insure sealing of any thin wall imperfections. With these conventional hand-held fluid testers, testing is performed by filling the fluid reservoir to a marked volume. This is typically done by line of sight and therefore the volume of test fluid introduced to the fluid reservoir may not be the same for all tests and may vary depending on the person doing the testing.
These conventional hand-held fluid testers have a number of important shortcomings. For example, the assembly of the electrodes and the thermistor to the reservoir wall is cumbersome and frequently requires the use of additional potting compounds or adhesives which are difficult to handle. The electrical connections between these devices and a testing circuit on a printed circuit board are typically provided via jumper wire leads which also must be individually handled and connected which increases labor associated with the assembly. Moreover, these devices do not provide any inherent test fluid volume controls so that wide variations in test results of and a lack of any meaningful calibration leads to unreliable results.